--- a/slides/slides09.tex	Wed Nov 18 01:53:01 2015 +0000
+++ b/slides/slides09.tex	Wed Nov 18 02:59:49 2015 +0000
@@ -117,19 +117,20 @@
 abstract class BExp 
 abstract class Decl
 
-case class 
-  Def(name: String, args: List[String], body: Exp) 
-                                          extends Decl
-case class Main(e: Exp) extends Decl
-
-case class Call(name: String, args: List[Exp]) extends Exp
-case class If(a: BExp, e1: Exp, e2: Exp) extends Exp
-case class Write(e: Exp) extends Exp
 case class Var(s: String) extends Exp
 case class Num(i: Int) extends Exp
 case class Aop(o: String, a1: Exp, a2: Exp) extends Exp
+case class If(a: BExp, e1: Exp, e2: Exp) extends Exp
+case class Write(e: Exp) extends Exp
 case class Sequ(e1: Exp, e2: Exp) extends Exp
+case class Call(name: String, args: List[Exp]) extends Exp
+
 case class Bop(o: String, a1: Exp, a2: Exp) extends BExp
+
+case class Def(name: String, 
+               args: List[String], 
+               body: Exp) extends Decl
+case class Main(e: Exp) extends Decl
 \end{lstlisting}
 
 \end{frame}